1. Field of the Invention
The present invention relates to a casting-thickness variable mold for continuous casting. More particularly, the present invention relates to a casting-thickness variable mold of the above kind which is able to form a mold cavity having a desired casting thickness by changing the dimension of short-side frames disposed between a pair of long-side frames that determines the width of the mold cavity (that is, the dimension corresponding to the thickness of a casting; hereinafter referred to as "the width-determining dimension").
2. Description of Related Art
In a conventional continuous casting system, when it is necessary to change the thickness of a casting, the currently used mold is replaced with a mold constructed to provide the desired thickness, and such replacement is performed each time a change in the casting thickness is needed (Related Art Example I). However, changing the mold size in this manner takes a long time. In addition, various types of molds, each being able to provide a fixed thickness, have to be prepared beforehand, thus incurring a high equipment cost.
In view of these problems, an apparatus has been proposed as a casting-thickness variable mold which allows short-side frames to be quickly replaced in an on-line condition of the apparatus (Japanese Utility Model Examined Publication No. 2-35386; Related Art Example II). FIG. 3 shows the basic construction of such a casting-thickness variable mold. The mold includes a pair of long-side frames, one of which is a stationary frame 1. The other long-side frame is a movable frame 2, which is disposed opposite the stationary frame. Short-side frames 51 and 52, having a certain width-determining dimension corresponding to a desired casting thickness, are disposed in a space between the long-side frames 1 and 2 in such a manner that the frames 51 and 52 can be replaced. Each short-side frame 51 or 52 is connected with a spindle 5 of a short-side moving device which is used in an operation for changing the casting thickness.
In Related Art Example II, when the casting thickness is to be changed, the short-side frames 51 and 52 currently used are disconnected from the spindles 5, and other short-side frames capable of providing a desired size are mounted.
With the mold of Related Art Example II, although operational efficiency is improved as compared with Related Art I, changing the casting thickness can still be troublesome because, each time such an operation is required, the spindles 5 must be disconnected from and re-connected to the short-side frames 51 and 52, and a water supply pipe, etc. (not shown) have to be disconnected and re-connected to the associated components. Another problem is that, although the spindles 5 can be connected to the substantially central positions of short-side frames 51 and 52 when these frames have a small width-determining dimension, the spindles 5 are inevitably connected to positions offsetting from the center in the case of short-side frames having a large width-determining dimension. In the latter case, when the short-side frames are being moved in the casting-thickness changing operation, these frames may be subjected to torsion, thereby damaging long-side copper plates 6.